Mycotoxin contamination in post-harvest crops poses significant health risks and economic losses. Aflatoxins, produced by Aspergillus species, are among the most toxic and carcinogenic mycotoxins. Traditional decontamination methods, such as chemical treatments and thermal processing, often compromise nutritional quality or leave residues. Hydrogen-based technologies, particularly hydrogen plasma and photocatalytic methods, offer promising alternatives for mycotoxin degradation without harmful byproducts. This article examines these approaches, their mechanisms, efficacy, and regulatory challenges.

Hydrogen plasma, a partially ionized gas containing reactive hydrogen species, can effectively break down mycotoxins. The process involves generating plasma through electrical discharges in a hydrogen-containing atmosphere. Reactive oxygen and nitrogen species (RONS), along with hydrogen radicals, interact with mycotoxin molecules, leading to oxidative degradation. Studies demonstrate that hydrogen plasma can reduce aflatoxin B1 levels by over 90% in treated crops. The efficacy depends on exposure time, plasma power, and the substrate's physical properties. For instance, thin-layer crops like grains show higher degradation rates compared to bulkier produce due to better plasma penetration.

The mechanism of mycotoxin degradation via hydrogen plasma involves multiple pathways. Hydrogen radicals (H•) and hydroxyl radicals (•OH) attack the double bonds and furan rings in aflatoxins, breaking their molecular structure. The lactone ring, critical for aflatoxin toxicity, is particularly susceptible to cleavage. Secondary reactions with ozone (O3) and peroxides further degrade the fragments into non-toxic compounds like CO2 and H2O. Research indicates that optimal plasma treatment parameters (e.g., 10–15 kV, 5–10 min exposure) achieve significant detoxification while preserving crop quality. However, scalability remains a challenge due to energy requirements and equipment costs.

Photocatalytic methods using hydrogen-based catalysts represent another viable approach. Titanium dioxide (TiO2) doped with hydrogen or combined with hydrogen-producing materials enhances photocatalytic activity under UV or visible light. The process generates electron-hole pairs that react with water and oxygen to produce •OH and superoxide radicals (O2•−). These radicals degrade mycotoxins by oxidizing their functional groups. Studies report 80–95% aflatoxin reduction in crops like maize and peanuts using hydrogen-modified TiO2 photocatalysts. The degradation efficiency correlates with light intensity, catalyst concentration, and treatment duration.

The photocatalytic mechanism involves adsorption of mycotoxins onto the catalyst surface, followed by radical-mediated oxidation. Aflatoxin B1’s difuran and coumarin moieties are primary targets, with degradation products identified as less toxic derivatives. Hydrogen incorporation into the photocatalyst improves charge separation and reduces electron-hole recombination, enhancing efficiency. For example, hydrogen-treated TiO2 nanoparticles show 30% higher degradation rates compared to untreated catalysts. However, catalyst recovery and reuse in large-scale applications require further optimization.

Efficacy studies highlight the potential of these methods but also reveal limitations. Hydrogen plasma achieves rapid mycotoxin degradation but may cause superficial crop damage if not carefully controlled. Photocatalysis offers gentler treatment but depends on light penetration, which varies with crop density. Comparative studies show that plasma treatment is more effective for surface contaminants, while photocatalysis suits bulkier crops with deeper mycotoxin infiltration. Both methods maintain nutritional quality better than thermal or chemical treatments, with minimal impact on proteins, vitamins, and fats.

Regulatory hurdles impede widespread adoption. Hydrogen plasma systems must comply with electrical safety standards and emissions regulations, as ozone and nitrogen oxides are byproducts. Photocatalytic methods face scrutiny over nanoparticle residues in food products. Regulatory agencies like the FDA and EFSA require extensive toxicity data for degradation byproducts and long-term crop safety studies. Current guidelines lack specific protocols for hydrogen-based mycotoxin remediation, necessitating case-by-case approvals. Harmonizing international standards is critical for commercial deployment.

Energy efficiency and cost are additional barriers. Hydrogen plasma systems consume 50–100 kWh per ton of treated crop, while photocatalysis demands UV lamps or solar concentrators. Scaling these technologies to industrial levels requires renewable energy integration to ensure sustainability. Pilot projects in Europe and Asia demonstrate feasibility, but high capital costs limit adoption in developing regions where mycotoxin contamination is most prevalent.

Future research should focus on optimizing reaction parameters, reducing energy consumption, and validating safety profiles. Hybrid systems combining hydrogen plasma and photocatalysis could leverage the strengths of both methods. For instance, plasma pretreatment could enhance photocatalyst performance by increasing surface reactivity. Advances in catalyst design, such as hydrogen-storing nanomaterials, may further improve efficiency.

In summary, hydrogen plasma and photocatalytic methods offer effective, residue-free solutions for mycotoxin degradation in post-harvest crops. Their mechanisms rely on reactive species that break down toxic structures while preserving crop quality. Despite promising efficacy, regulatory and economic challenges must be addressed to enable large-scale implementation. Collaborative efforts among researchers, industry, and policymakers are essential to integrate these technologies into global food safety frameworks.